September 25th, 2014, 12:58 PM | #1 |
ninjette.org sage
Name: Lane
Location: Medford, OR
Join Date: May 2014 Motorcycle(s): Ninja 250 (trackbike), CBR600RR, GS500F Posts: 588
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carbs - how the frak do they work?
So not my Ninjette, she's running fine.
My wife's bike, however.... It's an '07 GS500F. It hasn't been ridden in over 3 years now, and I had pulled the carbs, removed and cleaned the jets, and put it back together (I hope correctly). I can get it to start ok with the choke on. It won't idle though, without choke, and adjusting the idle doesn't seem to make a difference. Any ideas where I should start with the troubleshooting? There's a chance I didn't get all of the various interconnecting tubes in the right place, but I think I did. Should I borrow a carb sync tool and see if I can get that done first (although wouldn't it have to at least idle and stay running to do that)? I'm open to suggestions. Thanks. |
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September 25th, 2014, 01:02 PM | #2 |
Cat herder
Name: Gort
Location: A secret lair which, being secret, has an undisclosed location
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Googling "gs500 carburetor" yielded considerable video and troubleshooting content.
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September 25th, 2014, 01:25 PM | #3 |
ninjette.org guru
Name: Lee
Location: Monroe, LA
Join Date: Feb 2014 Motorcycle(s): Rebel 250s, Ninja 250s VN750s (currently nine total) Posts: 465
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When gas is left in a carb, it can obstruct the internal passages as well as the jets. Carb spray isn't a sufficiently aggressive cleaner to remove stubborn deposits. Sounds like your carbs are still dirty. Get a can of Berrymans Chem Dip (around $16 at the local Wal Mart) and soak only the metal parts for a minimum of 24-48 hours. Rinse well with water and blow out all the openings with high pressure compressed air. Or if you have access to a sonic cleaner, use that as it will clean it quickly.
The Chem Dip can be used several times before it becomes contaminated and needs to be replaced. Draining the carb before extended storage will keep the carbs from gumming up. |
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September 26th, 2014, 09:55 PM | #4 |
Old and slow
Name: Lohman
Location: Aiken, S.C.
Join Date: May 2014 Motorcycle(s): Suzuki TL1000R, Honda CBR600F3, Ninja 250 Posts: 889
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Carbs = magic...
However, you can learn magic. Yes as Flitecontrol said, gas, old gas... old gas that evaporates in a carb leaves lacquer or varnish... in very small passages and ports... two things that work, soaking in carb cleaner and blowing it out with high pressure air. may take two or three times... once you get them clean, they should work much better... having to keep the bike choked to keep it running at idle... = lacquer in the idle jets (the smallest) |
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September 26th, 2014, 10:00 PM | #5 |
ninjette.org certified postwhore
Name: Jason
Location: Monroe, MI
Join Date: May 2013 Motorcycle(s): '75 CB550:.'82 XV920:.'00 KLR650:.'00 EX250:.'08 Ninja 250 Posts: A lot.
MOTM - June '15
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I bought an ultrasonic cleaner specifically for carb work. If a carb comes off a bike, it now comes apart and takes a nice 20 minute long heated bath and it's worked on everything I have put in there!
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September 30th, 2014, 08:40 AM | #6 |
ninjette.org sage
Name: Lane
Location: Medford, OR
Join Date: May 2014 Motorcycle(s): Ninja 250 (trackbike), CBR600RR, GS500F Posts: 588
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So not just the jets, huh? I've looked at a couple of the various S500 videos, but not all of them yet. I'd love to just trailer it over to a professional, but I'm trying to learn how to do this stuff on my own to save money, and support my racing habit.....
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October 2nd, 2014, 01:29 PM | #7 |
IC2(SW)
Name: Kerry
Location: Pensacola
Join Date: Nov 2008 Motorcycle(s): . Posts: A lot.
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October 2nd, 2014, 01:30 PM | #8 |
ninjette.org certified postwhore
Name: Eric
Location: Iowa City
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Replace the pilot jets.
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October 2nd, 2014, 03:15 PM | #9 |
ninjette.org certified postwhore
Name: Frugal
Location: Dallas/Fort Worth (DFW)
Join Date: Mar 2010 Motorcycle(s): Several Posts: A lot.
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At the most basic level, carbs work using the Bournulli principle: http://en.wikipedia.org/wiki/Bernoulli%27s_principle
Essentially, the pressure of air in any given spot is related to its velocity. Carbs have a section with reduced area such as a venturi, and in that spot the air speed has to increase. It increases because the same amount of air is going through a smaller area. Because the speed increases the pressure decreases, and that draws fuel out of the float bowl through metered orifices called jets. But really, you still have solidified crap inside the orifices, passages, and jets in the carb. Carb spray or brake cleaner (my preferred fluid) should spray through all openings and passages. Removing all the jets, pilot tubes, needles, etc, is generally required when cleaning carbs that sat for a very long time. Also, remove the rubber bits like the diaphragms, O-rings, and gaskets before cleaning as most cleaning fluids will damage these "soft" parts. |
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October 3rd, 2014, 07:20 AM | #10 |
Old and slow
Name: Lohman
Location: Aiken, S.C.
Join Date: May 2014 Motorcycle(s): Suzuki TL1000R, Honda CBR600F3, Ninja 250 Posts: 889
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wow, that is a beautiful diagram of a CV carb.
you see the "pilot jet" (item #1) that is going to be your "it won't idle" problem area... that path, through the jet, to the up stream or down stream side of the butterfly, as well as the "idle mix screw"... all those path ways are VERY small, literally the size of a sewing needle. Maybe even smaller... very prone to varnish clogging... they have no moving parts and only the smallest delta P when operating so nothing to really clean them during normal ops... the main jet will always be in the "middle" right under the main venturi... the pilot will be another brass screw in type jet... but it will be off center somewhere under the float. that's where you want to spray the carb cleaner, and blow it out with compressed air until you can feel air blowing around the butterfly... back the idle mix screw out all the way and clean... you can try and shut it (count the turns going in) and then put the same amount of turns coming back out when you assemble after cleaning... 2.5 turns is a common number... although some are 4 turns open... be sure to clean your choke ports as well... the worst thing for a carb is to sit full of gas, and then dry out... everything gets clogged and coated. |
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